Mechanical stoker



May 1, 1 934., J w JR 1,956,939

' MECHANICAL sTbKm Filed May 4. 1931 2 Sheets-Sheet 1 INfENTbR Pig/7nd? 1 ATTORNEYS May 1, 1934. J, WYNN, JR

' MECHANICAL STOKER 2 sheets-sniii. 2

Fil'ed m 4, 1951 .INVENTOR BY Wig/I212 ATTORNEK;

Patented May 1, 1934 UNITED STATES.

PATENT OFFICE The invention relates more particularly to a stoker mechanism utilized for the prevention of the formation of clinker within the furnace served by the stoker.

The improved apparatus is adapted to accomplish the feeding of slack, or other suitable, finely divided fuel into the tuyre of a furnace, which is surrounded by an air blast of such pressure and volume, as compared to the volume and velocity of the fuel within the blast zone, or primary combustion zone, that the fuel will be reduced to coke before passing out of the blast zone, and into the secondary combustion zone, where the natural infiltration of air, due to ordinary chimney draft, completes combustion of the fuel.

Obviously, no ash can be produced within the high temperature blast zone, except by the burning of very fine particles of coal or carbon, which, being extremely light in weight, are blown out of the blast zone, and into the secondary combustion zone before the mass thereof becomes of sufficient size or volume to form clinkers.

The term clinker, as used herein, is intended to designate large masses of fused ash, which must ordinarily be removed by hand. As is well known, coal or coke will not clinker, the clinker being the fusion of the foreign matter within the coal or coke, namely, ash, sulphur, pyrites, etc.

Consequently, if the coal is reduced to coke, and means provided for eliminating the ash from the fusion zone, before the ash accumulates in a mass sufficient to form clinker, it is evident that no clinker will be formed.

Therefore the present invention contemplates the production of an air blast directed inward, and upward, and of uniform pressure surrounding, and in contact with, the coal, the air mixing with the coal immediately below the point of expansion of the coal from the tuyere into the combustion chamber.

The air blast is directed inward, and upward, in order to cause the flame to concentrate its maximum heat away from the secondary combustion zone, so that a fusion temperature will not develop in the secondary combustion zone.

The object of the mechanical stoker means of the present improvement is to provide simple means of installation and accessibility for repair; means for removing dust from the air chamber of the tuyre box; means for maintaining the tuyere concentric with the fire ring; means for adjusting the height of the grate with respect to the incoming coal feed and the fire ring; means for agitating the grate to remove ash therefrom: means for adjusting the movement of the grate ir.

relation to the ash constituents of the coal; means for holding the grate concentric with the tuyere and supporting the same; and means for breaking up the coke bed, permitting the ash to sift through before the mass of ash is sufficiently large to form a clinker.

The above, together with other objects which will be later referred to, or which will be obvious from the accompanying drawings and the following detail description, may be attained by constructing the mechanism in the manner illustrated in the accompanying drawings, in which Figure 1 is a vertical, longitudinal section through the improved stoker mechanism;

Fig. 2, a plan sectional view of the same;

Fig. 3, an elevation of the eccentric disk by means of which the agitation of the grate is regulated; and

Fig. 4, an elevation of the slotted bracket which cooperates with the eccentric disk for agitating the grate.

Similar numerals refer to similar parts the lower casting 12, located concentrically with- 8 in the furnace shell 13, and provided with the neck 14 to which the tubular housing 11 is connected, the screw 10 extending through said neck and into the fuel chamber 15 provided within said casting 12.

The casting 12 has the inner walls 16, forming the walls of thefuel chamber 15, and the spaced outer walls 1'7, forming an air box surrounding the fuel chamber and arranged to be supplied with air under pressure from a blower or other suitable means.

The inner end of the conveyor screw' shaft is provided with a squared socket 18, for detachably receiving the squared end 19 of a shaft 20, which is journaled through the .bearing 21, formed in the casting 12.

For the purpose of preventing longitudinal movement of the shaft 20, a peripheral groove 22 may be formed therein, within the bearing 21, and a pin 23 may be located transversely through the bearing and into said groove;

A disk 24 may be welded or otherwise connected eccentrically to the end of the shaft 20, and provided with a plurality of apertures 25 located at different distances from the center of the shaft 20.

An upper casting 26 is provided upon the top of the casting 12, the meeting edges 27 of said castings being surface ground and fitted together as shown in Fig. 1.

This upper casting has an inner annular wall 28, and an outer annular wall 29, which walls form continuations of the inner and outer walls 16 and 17 respectively of the lower casting 12.

Lugs 30 and 31 are formed upon the lower and upper castings respectively adjacent to their meeting edges, and screws 32 or the like are inserted into said lugs for detachably connecting the two castings together.

Webs or ribs 33 are provided at intervals within the interior of the upper casting, connecting the inner and outer walls 28 and 29 thereof, and at their upper ends these walls are connected by the annular wall 34 which, together with the upper' portions of the walls 28 and 29, forms the tuyere.

The inner wall 28 is provided, at a point near its upper end, with a continuous, annular slot 35, which in cross section, as shown at 35, is inclined or angled upward toward the center of the fuel chamber, for the purpose of producing a blast of air in an inward and upward direction toward the center of the fuel bed.

This air blast is directed inward and upward for the purpose of causing the flame to concentrate its maximum heat away from the secondary combustion zone so that a fusion temperature will not develop therein. The air blast creates what is termed the blast zone or primary combustion zone, while the portion of the mechanism surrounding the tuyre is termed the secondary combustion zone.

The grate 36 is formed of two similar, half annular portions, bolted together at 37, and surrounding the outer wall 29 of the upper casting. Spaced, inwardly extending lugs 38 are formed around the interior of the grate, and rest upon the lugs 31 of the upper casting to support the grate in operative position.

At this point it should be stated that the upper and lower castings are formed separately and arranged to be detachably connected together inorder that an upper casting of any desired or necessary height may be used so as to adjust the height of the grate with respect to the incoming coal feed, as well as the fire ring 39.

The grate is adapted to be oscillated around the upper casting by means of a depending bracket 40, attached to the under side of the grate and provided with a vertical slot or groove 41, which receives a pin 42, arranged for selective engagement in any of the apertures 25 of the eccentric disk 24.

Thus, as the conveyer screw rotates, the grate will be oscillated around the outer wall 29 at any desired length of throw, depending upon which of the apertures 25 is engaged by the pin 42. As the grate is thus oscillated, the ash will be shaken through the openings 4'7 thereof and also through the openings or cut-out portions 48 between the lugs 38 around the inner portion of the grate to prevent the accumulation of ash at this point so as to obviate the possibility of formation of a clinker around the tuyere.

Lugs 49 are formed upon the upper portion of the outer wall 29 and extend radially outward over the inner portion of the grate to assist in scraping the ash away from the inner portion of the grate as the grate is oscillated. A further object of these lugs is to help support the heated mass of fuel above the grate so that fused particles of pyrites have an openspace to fall through so as not to congest this portion of the grate with ash dust, thus further assisting in the prevention of a mass of material of low fusion temperature being formed around the tuyre, such as would be formed by a ball of sulphur or iron impurities which enter the fusion zone.

The space being more or less clear and the grate moving the heated particles, causes them to fall on a rapidly chilling and moving surface which cools these particles below a refming point before again coming in contact with the molten particles of pyrites and impurities. Another object of these lugs is to break up the coke mass and force the coke toward the outer portion or periphery of the grate, thus facilitating combustion and covering the grate area more uniformly with the fuel bed.

It will be seen that since the periphery of the grate moves a greater distance than the inner circumference thereof, and the fire is more intense near the center of the grate, these lugs are' especially advantageous around the inner circumference of the grate both to break up the coke mass and scrape the ash through the grate so that the ash dust may sift through the grate at this point.

The above action is also assisted by forming several small openings 50 spaced around the periphery of the tuyere and preferably located in pairs one upon each side of each lug 49 and preferably inclined upward and outward as shown, so as to blow the ash dust away from the tuyere and inner portion of the grate and to add a small quantity of airto aid combustion in the secondary combustion zone, but not a suificient amount of air to produce a fusion temperature, thus preventing unburned carbon from passing through the grate at a point where a maximum agitation is produced.

The tuyre and fuel chamber are held concentrio with the fire ring 39 by means of a plurality of braces or stays 51 connected to both of said members as best shown in Fig. 1 of the drawings. Dust may be cleaned from the air box by removing the upper casting from the lower casting, thus giving access to the interior of the air box.

As will be seen from Fig. 1 of the drawings, the air blast is directed inward and the annular slot 35 just below the point of expansion of the fuel as the same passes upward through the fuel chamber and outward over the tuyere onto the grate. The object of directing the air blast at a point just below this point of expansion of the fuel is to completely consume a small portion of the coal around the periphery of the fuel bed so that as the heat expands the coal it will not cause it to choke the air passage 35.

From the above it will be seen that the process of preventing clinker as carried out by the mechanism illustrated and above described consists in feeding coal surrounded by an air blast of such pressure and volume in relation to the volume and velocity of the coal passing through the blast zone that the coal may be reduced to coke before passing entirely out of the blast zone and over the tuyre onto the grate, into the secondary combustion zone, where the natural infiltration of air, due to chimney draft, completes combustion. It will also be evident that no ash is produced within the primary combustion or blast zone, except the burning of very fine particles of coal or carbon which are so light in weight that they are blown out of the blast zone into the upward through secondary zone before the mass becomes of sufficient size toform clinkers.

Any small clinkers which may start to form around the tuyere will be disintegrated by what may be termed the secondary blast passing through the small openings 50 which will rapidly cool the small clinkers in the process of formation and permit them to drop through the grate as the same is oscillated.

I claim;

1. In a furnace, a fuel chamber surrounded by an air box having a tuyere at its upper end, a grate surrounding the air box, and means for oscillating the grate, the tuyere being provided with an inwardly and upwardly directed annular slot communicating with the air box and arranged to produce an air blast in the fuel bed entirely below the point where the fuel is expanded by heat, and spaced lugs upon the tuyre extending outward over the inner portion of the grate.

2. In a furnace, a fuel chamber surrounded by an air box having a tuyere at its upper end, a grate surrounding the air box and rotatable relative thereto, and means for oscillating the grate, the tuyere being provided with an inwardly and upwardly directed annular. slot communicating with the air box and arranged to produce an air blast in the fuel bed entirely below the pointwhere the fuel is expanded by heat, there being outwardly extending lugs upon the air box for supporting the grate, and inwardly disposed lugs upon the grate resting upon said outwardly disposed lugs, whereby a partial rotation of the grate will permit detachment thereof from the tuyre.

3. In a furnace, a fuel chamber surrounded by an air box having a tuyre at its upper end, a gratesurrounding the air box, and means for oscillating the grate, the tuyere being provided with-an inwardly and upwardly directed annular slot communicating with the air box and arranged to produce an air blast in the fuel bed entirely below the point where the fuel is expanded by heat, there being outwardly extending lugs upon the air box for supporting the grate, and spaced lugs upon the tuyre extending outward over the inner portion of the grate.

. 4. In a furnace, a fuel chamber surrounded by an air box having a tuyere at its upper end, a grate surrounding the air box, and means for oscillating the grate, the tuyere being provided with an inwardly and upwardly directed annular slot communicating'with the air box and arranged to produce an air blast in the fuel bed entirely below the point where the fuel is expanded by heat-there being outwardly extending lugs upon the air box for supporting the grate, inwardly disposed lugs upon the grate resting upon'said outwardly disposed lugs, and spaced lugs upon the tuyre extending outward over the inner portion of the grate.

5. In a furnace, a fuel chamber surrounded by an air box having a tuyere at its upper end, a grate surrounding the air box, and means for oscillating the grate, the tuyere being provided with an inwardly and upwardly directed annular slot communicating with theair box and arranged to produce an air blast in the fuel bed entirely below the point where the fuel is expanded by heat, spaced lugs upon the tuyere extending outward over the inner portion of the grate, and there being outwardly disposed apertures in the tuyere communicating with the air box and disposed on each side of said lugs upon the tuyere.

6. In a furnace, a fuel chamber surrounded by an air box having a tuyere at its upper end, a grate surrounding the air box, and means for oscillating the grate, the tuyre being provided with an inwardly and upwardly directed annular slot communicating with the air box and arranged to produce an air blast in the fuel bed entirely below the point where the fuel is expanded by heat, there being outwardly extending lugs upon the air box for supporting the grate, spaced lugs upon the tuyre extending outward over the inner portion of the grate, and there being outwardly disposed apertures in the tuyere communicating with the air box and disposed on each side of said lugs upon the tuyere.

7. In a furnace, a fuel chamber surrounded by an air box having a tuyere at its upper end, a grate surrounding the air box, and means for oscillating the grate, the tuyere being provided with an inwardly and upwardly directed annular slot communicating with the air box and arranged to produce an air blast in the fuel bed en-, 

